Design and synthesis of new materials for energytechnologies

Claudia Felser

Co-workers in Dresden and elsewhereDresden group

SPP 1386

The Philosophy:

The Rational Design

ConceptGoal: Directed Design of new

multifunctional materials

our tool box: the periodic table

The „Designer“-Material

Heusler compounds

Diamond ZnS Heusler XYZ C1b X2YZ L21

Graf T, Felser C, Parkin SSP, IEEE TRANSACTIONS ON MAGNETICS 47 (2011) 367Graf T, Felser C, Parkin SSP, Progress in Solid State Chemistry Chemistry 39 (2011) 1

Semiconductors and Solarcells

Materials: Ternary Semiconductors …Heusler C1b

Zn

Cd

Li

1 + 2 + 5 = 8

2 + 6 = 8

S

P

Zincblende structure

• Semiconductors • with the magic electron number 8• MgAgAs Structure • C1b - Half Heusler- or Nowotny-Juza

compounds

Graf, Felser, Parkin, Progress in Solid State Chemistry (2011)

Zhang et al Adv. Funct. Mater. 2012,

… High through put

DFT-calculations of 650 Heusler compounds

LiCuS

LiZnP

Kieven, Naghavi, Klenk, Felser, Gruhn, PRB 81, 075208 (2010)

2.0eV

CdS substituted by LiCuS

Kieven et al., Phys. Rev. B 81, (2010) 075208

Ternary Semiconductors …

LiCuS instead of CdS

Ternary Semiconductors …

Synthesis: Li + CuS LiCuSalumina tubes and sealed silica tubes

Synthesis temperature:1000°C black powder cubic structure

Synthesis temperature: 450-500°C

Beleanu, et al. to be published

Li1+xCu1-xS

Beleanu, et al., to be published

EgapLiCuS ~ EgapCdSe

Thermoelectric applicationsand

Phase separation

Thermelectrics

Automotive (BMW & GM)

G. J. Snyder and E. S. Toberer. Nature Materials, 7 (2008) 105

Thermelectrics

n = charge carrier concentration

m* = charge carrier effective mass

µ = charge carrier mobility

G. J. Snyder and E. S. Toberer. Nature Materials, 7 (2008) 105

TSZTκσ2

=

P. H. Ngan, D. V. Christensen,G. J. Synder, L. T. Hung,S. Linderoth and N. Pryds. Phys.Status Solidi A. 2013, 9

The Materials

The Recipe

Mike Coey, Magnetism and Magnetic Materials

Diamond ZnS Heusler XYZ C1b X2YZ L21

3 + 5 = 8 3 + 5 = 8

Ga As

MgLi

1 + 2 + 5 = 8

As

Zr Ni

4 + 10 + 4 = 18

Sn

Typ Material Price in $/kg (metals)

V-VI Bi2Te3 140 IV-VI PbTe 99 Zn4Sb3 Zn4Sb3 4

p-MnSi1.73 24 n-Mg2Si0.4Sn0.6 18 Si0.80Ge0.20 660

Silicides

Si0.94Ge0.06 270 Skutterutides CoSb3 11 Half-Heusler TiNiSn 55 n/p-Clathrate Ba8Ga16Ge30 1000

w ithout Ba Oxides p-NaCo2O4, 17

w ithout Na, O Zintl Phasen p-Yb14MnSb11 92 Th3P4 La3-XTe4 160

State of the art and cost

Thermoelectric100 200 300 400 500 600 7000.0

0.2

0.4

0.6

0.8

1.0

1.2

1.4

1.6 n-typ p-typ

TiFe0.15Co0.85

SbTiFe0.3

Co0.7Sb

Ti 0.6Hf 0.4

Co 0.87Ni 0.13

Sb

Zr0.5Hf0.5

CoSb0.8Sn0.2Zr 0.2

5Hf 0.7

5NiSn 0.9

75Sb 0.0

25

Zr0.5Hf0.5

NiSn

Zr 0.25Hf 0.2

5Ti 0.5

NiSn 0.9

94Sb 0.0

06

Zr 0.25Hf

0.25Ti 0.5

NiSn

0.998

Sb0.0

02

Fi

gure

of m

erit

ZT

Temperatur [°C]

TSZTκσ2

=

κ: thermal conductivityT: absolute temperature

σ2SPF =Power factor

σ: electricalconductivity

S: Seebeck

coefficient

0

1

2

3

4

5

-1.0

-0.5

0.0

0.5

1.0

-0.8 -0.6 -0.4 -0.2 0.0 0.2 0.4 0.6 0.805

10152025

NiTiSnT = 300 K

elec.

cond

uctiv

ityσ/τ [

1019

(Ωm

s)-1]

Se

ebec

k co

efici

ent

S(T)

[mVK

-1] electrons

holes

Metall

Powe

r fac

tor

PF(T

) [10

10 W

/(K2 s)]

Chemical potential δµ / ∆Egap

Metalldoped semiconductors

Band gap

𝑆𝑆 𝜎𝜎2

κ

Key: Increase Seebeck Increase electrical conductivity Decrease thermal conductivity

Tunability

Strange semiconductors…

F. Yan et al. arXiv:1406.0872TaIrGe

Thermal conductivities

G. J. Snyder and E. S. Toberer. Nature Materials, 7 (2008) 105

R. Asahi et al. J. Phys.: Cond. Mat. 20 (2008) 64227K. Miyamoto et al. Appl. Phys. Express 1 (2008) 081901 VK Zaitsev et al. PRB 74 (2006) 045207

The challenge: low thermal conductivity, especially for p-type

-1.0 -0.5 0.0 0.5 1.0

-400

-200

0

200

400

Seeb

eck

coef

ficie

ntS(

µ)[µ

VK-1

]

Chemical potentialµ[eV]

TiNiSn at 500K

Ouardi et al , Appl. Phys. Lett. 99 (2011) 152112.

Band engineering

0 100 200 300 4000,0

0,1

0,2

0,3

0,4

0,5

NiZr0.5Hf0.5Snsingle crystal

ZT

Temperature T [K]

0 100 200 300 400

-400

-300

-200

-100

0

Seeb

eck

coef

ficie

nt S

(T) [

µVK

-1]

Temperature T [K]

NiZr0.5Hf0.5Snsingle crystal

Band Gaps

Ouardi et al. , Phys. Rev. B 82 (2010) 085108

Stable nano structures

80 µm80 µm

1000°C,2 weeks

Köhne, Felser, Graf, Elmers, Bosch, University Mainz, published 2011, US Patent 20,130,156,636 M. Schwall et al. Adv. Funct. Mater. 22 (2012) 1822

Substitution in Ti0.3Zr0.35Hf0.35NiSn

15

n-Typ

p-Typ

DFT CPA calculations

acceptor

EF

donor

M*= Sc

M*= V, Nb

Long term stability of TE properties n-type

Julia Krez, Benjamin Balke, Claudia Felser, Wilfried Hermes and Markus Schwind, submitted preprint arXiv:1502.01828, 2015

Ti0.3-xVxZr0.35Hf0.35NiSnREM Measurements Transport n-Typ

Charge carrier concentration

Max. zT1 @ 800K

x

x x

x

Krez et al. , to be submitted

Ti0.3-xScxZr0.35Hf0.35NiSn (x = 0.01-0.05) Transport p-TypeREM measurements

Max. zT0.3 @ 700K

500µm

Krez et al., preprint arXiv:1502.01828, 2015

Band Gap Modelling

Schmitt et al. in collaboration with Jeff Snyder, Mater. Horiz., 2015, 2, 68

Estimation of the band gap for different n-type and p-type HH compounds using the Goldsmid–Sharp formula (Eg ~ 2eSmaxTmax) [eV]

p-type HH Zr1-xScxNiSn: • large mobility difference between electrons and holes

explains the difference in the thermopower band gap• between n-type and p-type • high electron-to-hole weighted mobility ratio (~5)

p-type Heusler compounds Ti1−xHfxCoSb0.85Sn0.15

Main reflection (220) of Ti1−xHfxCoSb0.85Sn0.15 with the indicated ratios of Ti to Hf.

High resolution XRD

HfCoSb0.85Sn0.15

Rausch et al, submitted preprint arXiv:1502.03336

Enhanced thermoelectric performance in the p-type half-Heusler (Ti/Zr/Hf)CoSb0.8Sn0.2system via phase separation

Rausch, Balke, Ouardi, Felser, Phys.Chem.Chem.Phys., 16 (2014), 25258.

100 200 300 400 500 600 7001.0

1.5

2.0

2.5

3.0

3.5

4.0

100 200 300 400 500 600 7000.0

0.2

0.4

0.6

0.8

1.0(b)

Powe

r fac

tor S

²σ [1

0-3W

/K²*

m]

(a)

Figu

re o

f mer

it ZT

Temperature [°C]

Ti/Hf best TE-properties !

Applying the concept of phase sep. to p-type

Charge carrier concentration optimization

The p-type Half-Heusler compound Ti0.3Zr0.35Hf0.35CoSb1−xSnx

1021 5x1021 10220

100

200

300

400

0.0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

Seb

eck

coef

ficien

t S [µ

V/K]S

Carrier concentration n [cm-3]

@ 610 °C(b)

σ S2σ

κ Fig

ure o

f mer

it ZT

ZT

Rausch et al, to be published

p-type Heusler compounds Ti1−xHfxCoSb0.85Sn0.15

Rausch et al, submitted to Adv. Energy. Mater., preprint arXiv:1502.03336

p-type Heusler compounds Ti1−xHfxCoSb0.85Sn0.15

Rausch et al, submitted to Adv. Energy. Mater., preprint arXiv:1502.03336

1021 2x1021 3x1021 4x10210

50

100

150

200

250

300

350

400

450

0.0

0.2

0.4

0.6

0.8

1.0

Seb

eck

coef

ficie

nt S

[ µV

/K]

S

Carrier concentration n [cm-3]

@ 610 °C(b)

σ

S2σ

κ

Fig

ure

of m

erit

ZT

ZT

HfTi Ti0.5Hf0.5

Ti0.3Zr0.35Hf0.35CoSb1-xSnx

Open symbolsTi1-xHfxCoSb0.85Sn0.15

Thermoelectric applicationsand

Topological insulators

KF Hsu et al. Science 303 (2004) 819

TopologicalInsulator

Yan, et al, PRB 85 (2012) 165125, arXiv:1104.0641 Yan et al. Phys. Status Solidi RRL 7 (2013) 13

Good TI are good thermoelectrics

Ouardi, et al., Appl. Phys. Lett. 99 (2011) 211904.

YPtBi

YPtBi

Topological insulators and thermoelectrics

Chandra Shekhar et. al. APL 100, 2152109 (2012).Chandra Shekhar et al. PRB 86, 155314 (2012)Chandra Shekhar et al., preprint arXiv:1502.04361

Zhipeng Hou et. al. arXiv:1502.03523

Properties

Graf, Felser, Parkin, IEEE TRANSACTIONS ON MAGNETICS 47 (2011) 367Graf, Felser, Parkin, Progress in Solid State Chemistry 39 (2011) 1